Recovery of alkyl fluoride in alkylation of isoparaffin with ethylene and a higher olefin promoter

ABSTRACT

IN THE ALKYLATION OF AN ISOPARAFFIN WITH AN OLEFIN IN THE PRESENCE OF HYDROFLUORIC ACID AS CATALYST WHEREIN THE TOTAL OLEFIN FEED AND/OR ISOPARAFFIN STREAM INCLUDES OR IS CONVERTED IN PART TO PROPANE CONTAINING STREAM, SAID OPERATION IS FOUND IN A PROPANE CONTAINING STREAM, SAID STREAM IS CONTACTED WITH LIQUID HYDROGEN FLUORIDE TO EXTRACT THE ALKYL FLUORIDE FROM THE PROPANE AND THE THUS ENRICHED HYDROGEN FLUORIDE IS CHARGED TO THE ALKYLATION, THE PROPANE BEING RECOVERED FROM THE USUAL HYDROGEN FLUORIDE STRIPPER.

3,751,517 Aug' 7 w73 T. HuTsoN. JR., Erm.

ATION oF IsoPoRAFFIN WITH EFIN PROMOTER RECOVERY OF ALKYL FLUORIDE IN ALKYL ETHYLENE AND A HIGHER OL Filed March 3. 1971 denser accumulator. Phase separation occurs in 27. A portion of liquid phase hydrocarbon from 27 is passed by 28 and 29 as feed to lHF stripper 30. Propane liquid, substantially free of HF and ethyl fluoride, is recovered via 31. The propane stripper is reboiled as shown. Another portion of the liquid phase hydrocarbon is passed via 28 and 40 to the upper portion of depropanizer 14 as re'ux. HF is removed via 32 as vapor from VHF stripper 30 and charged to the lower portion of extractor 16. The purified liquid phase HF stream from accumulator 27 is charged via 52, along with lean HF from conduit 51, as solvent for ether uoride which is introduced into extraction tower 16 via conduit 15. Normal butane vapor is recovered from isostripper 9 via conduit 37. Isostripper 9 is reboiled as shown. Debutanize-d alkylate is recovered via conduit 38. Additional isobutane for recycle is passed via 33 from depropanizer 14 and to reactor 5. Depropanizer 14 is reboiled as shown.

SPECIFIC EXAMPLE Tons/day Barrels/day 375. 6 370. 2 3. 1 5. 7 781. 6 n-B utane 32. 7

Total 1, 563. 2

Combined reactor feed (less HF to 5):

Ethylene 388. 6 Ethyl uoride-. Butylene- Ethane- 6. 2 93. 9 Propane 686. O 7, 740. 9 Isobutano 12, 787. 0 129, 940. 2 n-Butane 36 352. 4

Total Isostripprr overhead product (10):

TOal

Depropanizer feed (13):

Ethylene Ethyl uoride. Butylene Eth ana i Propane Isobutane n-Butane HF acid Total HF extractor feed (15):

Ethylene Ethyl fluoride Butylene Ethane Propane Isobutane. n-B utane HF acid Total Depropanizer kettle product (33):

Ethylene Ethyl uori de Butylene Ethane Propane Isobutane.

Total 6, 004. 4

TABLE-Continued Tons/day Barrels/day HF acid degassng column feed (17):

Light hydrocarbons 397. 4 4, 038. 6 HF acld 1, 592. 7 9, 104. 7 Water 16. l 92. 0 Acid soluble oils l 0. 3

Total 2, 006. 5

Overhead from degasslng column (20):

Light hydrocarbons- 397. 4 4,038. 6 HF acid. 402.0 2, 298.0 Water. 4.0 22. 9 Acid solubl 0 Total 803. 4

Bottoms from degassing column (21):

Light hydrocarbons HF acid Water. Acid solu Total Rich HF acid from extractor (25):

Propane 337.3 3 806.1 Ethyl fluoride- HF acld Propane product (31).. n-Butane product (37). Product alkylate (38) Norm-Propane purity, 99|%; n-butane purity, 90.8%.

ad o 1, 524. 1

Process conditions:

Catalyst/hydrocarbon vol. ratio to reactor 4:1 iCt/total olefin mol ratio to reactor 5:1 Reactor temperature, F 90 Reactor pressure 190 Reactor residence time, seconds 140 Butylene/ethylene plus CzHnF, weight ratio. 0. 3:1 Ethylene conversion (per pass), percent 93.5 Debutanized alkylate yield:

bs./1b. efin 2. 04 Bb1./100 lbs. olen 0.871 Extractor (16):

Pressure, p.s.i.g 250 Temperature, F 120 Weight ratio liquid HF solvent to 02H51? in feed 1. 6:1 Alkylate properties (38):

API gravity 79. 3 Density, lbs/gal 5. 587 Avg. mol weight, lbs/mol. 90. 4 Research octane (0 cc. TEL) 100. 4 Motor octane (0 cc. TEL) 95. 1

We have observed that ethylene conversion is a function of the amount of heavier olefin (heavier than the required ethylene) promoter used in our process. The higher amount of heavier olen increased the conversion of ethylene to alkylate. Also, the heavier alkyl uoride produced in the alkylation step is converted to additional high quality alkylate in the presence of the added heavy olen.

The isoparaffins which can be used in our process include isobutane and/or isopentane. The olefins, in addition to the required ethylene, can include propylene, butylenes, amylenes, and hexenes, either alone or in combination.

The ranges of isoparaflins to olens mol ratios can be about 1.5 to 1 up to about 20 to 1.

The catalyst to hydrocarbon volume ratios can be about 1 to 1 to about 10 to l.

The HF catalyst used can have about Weight percent up to about weight percent HF, other components being water, usually less than about 5 weight percent, and acid soluble oils.

Reactor temperatures can be about 40 F. to about 175 F. with pressures being suicient to maintain the now preferred liquid phase system.

The weight ratio of liquid HF solvent to ethyl fluoride to be absorbed can range from about 1 to l up to about 5 to 1, at temperatures and pressures to minimize yield of liquid propane out of bottom of tower.

Fractionation conditions are well known in the prior art.

Although the invention has been described as being primarily applicable in its now contemplated best mode due to production to diisopropyl from isobutane and ethylene employing a higher olen, e.g., isobutylene to promote the reaction it will be obvious to one skilled in the art in possession of this disclosure having studied the same that the invention and its concepts can have other applications.

vReasonable variation and modification are possible within the scope of the foregoing disclosure, drawing and the appended claims to the invention the essence of which is that alkyl uoride and propane are separated in an alkylation operation by extraction or the alkyl uoride from the propane using liquid HF catalyst, which can be recycled, and that propane is recovered from the extracted propane stream by stripping HF therefrom, substantially as described.

We claim:

1. A process for the alkylation of an isoparaiin with ethylene and in the presence of a higher oleiine promoter with a catalyst consisting essentially of hydrogen tinoride which comprises conducting said alkylation in an alkylation zone to produce an alkylation eiuent, separating from said eiuent an alkylate containing hydrocarbon phase and a hydrogen uoride phase, recovering from said hydrocarbon phase an isoparain-containing stream also containing hydrogen iiuoride, propane and alkyl iiuoride including ethyl tiuoride, returning a portion of said stream to said zone, passing another portion of said stream to a depropanizer zone, separating in said depropanizer zone an isoparain stream from a lighter stream containing HF, alkyl fluoride including ethyl fluoride and propane, passing said lighter stream to an extraction zone, subjecting said lighter stream in said extraction zone to solvent extraction with liquid HF to remove alkyl uoride including ethyl uoride into said liquid HF thus generating an extracted stream of propane containing HF, and an extract stream containing liquid HF and alkyl iiuoride including ethyl fluoride and passing said extract stream to said alkylation zone.

2. A process according to claim l wherein the stream containing propane and HF is passed to an HF stripping zone, in said stripping zone HF is stripped from said propane and propane is recovered as a separate stream.

3. A process according to claim 1 wherein the isoparain is at least one of isobutane and isopentane and the higher olefin is at least one of a butylene, an amylene and a hexene.

4. A process according to claim 1 wherein the isoparaiiin is isobutane, the olefin is isobutylene and the alkyl uoride is essentially ethyl uoride.

References Cited UNITED STATES PATENTS 3,209,051 9/1965 Bauer et al. 260-683A8 2,542,927 2/1951 Kelley 26o-683.48 2,387,162 lOl/1945 Matuszak 260-683-48 2,320,629 6/1943 Matuszak 260-683.42 2,392,048 l/l956 Kassel 260-683.41

DELBERT E. GANTZ, Primary Examiner G. J. CRASANAKIS, Assistant Examiner U.S. Cl. XR. 260-683.5l 

